Four letter words with double letters in the middle?

Proper Words include: book, boom, boon, boor, boot; cook, cool, coop, coot; doom, door; food, fool, foot; good, goon; hood, hook, hoop, hoot; look, loom, loop, loot; mood, moon, moot; noon; pool, poop, poor; rood, roof, rook, room, root; soon, soot; took, tool, toot; wood, woof, wool. There are also some informal or slang Words, like boob, coon and toon.